Modified: trunk/Source/WebCore/platform/audio/SincResampler.cpp (98791 => 98792)
--- trunk/Source/WebCore/platform/audio/SincResampler.cpp 2011-10-29 01:31:04 UTC (rev 98791)
+++ trunk/Source/WebCore/platform/audio/SincResampler.cpp 2011-10-29 01:47:50 UTC (rev 98792)
@@ -32,6 +32,7 @@
#include "SincResampler.h"
+#include "AudioBus.h"
#include <wtf/MathExtras.h>
using namespace std;
@@ -70,11 +71,13 @@
, m_kernelSize(kernelSize)
, m_numberOfKernelOffsets(numberOfKernelOffsets)
, m_kernelStorage(m_kernelSize * (m_numberOfKernelOffsets + 1))
- , m_virtualSourceIndex(0.0)
+ , m_virtualSourceIndex(0)
, m_blockSize(512)
, m_inputBuffer(m_blockSize + m_kernelSize) // See input buffer layout above.
, m_source(0)
, m_sourceFramesAvailable(0)
+ , m_sourceProvider(0)
+ , m_isBufferPrimed(false)
{
initializeKernel();
}
@@ -122,28 +125,85 @@
void SincResampler::consumeSource(float* buffer, unsigned numberOfSourceFrames)
{
- ASSERT(m_source);
- if (!m_source)
+ ASSERT(m_sourceProvider);
+ if (!m_sourceProvider)
return;
- // Clamp to number of frames available and zero-pad.
- unsigned framesToCopy = min(m_sourceFramesAvailable, numberOfSourceFrames);
- memcpy(buffer, m_source, sizeof(float) * framesToCopy);
+ // Wrap the provided buffer by an AudioBus for use by the source provider.
+ AudioBus bus(1, numberOfSourceFrames, false);
+ bus.setChannelMemory(0, buffer, numberOfSourceFrames);
- // Zero-pad if necessary.
- if (framesToCopy < numberOfSourceFrames)
- memset(buffer + framesToCopy, 0, sizeof(float) * (numberOfSourceFrames - framesToCopy));
-
- m_sourceFramesAvailable -= framesToCopy;
- m_source += numberOfSourceFrames;
+ m_sourceProvider->provideInput(&bus, numberOfSourceFrames);
}
+namespace {
+
+// BufferSourceProvider is an AudioSourceProvider wrapping an in-memory buffer.
+
+class BufferSourceProvider : public AudioSourceProvider {
+public:
+ BufferSourceProvider(float* source, size_t numberOfSourceFrames)
+ : m_source(source)
+ , m_sourceFramesAvailable(numberOfSourceFrames)
+ {
+ }
+
+ // Consumes samples from the in-memory buffer.
+ virtual void provideInput(AudioBus* bus, size_t framesToProcess)
+ {
+ ASSERT(m_source && bus);
+ if (!m_source || !bus)
+ return;
+
+ float* buffer = bus->channel(0)->data();
+
+ // Clamp to number of frames available and zero-pad.
+ size_t framesToCopy = min(m_sourceFramesAvailable, framesToProcess);
+ memcpy(buffer, m_source, sizeof(float) * framesToCopy);
+
+ // Zero-pad if necessary.
+ if (framesToCopy < framesToProcess)
+ memset(buffer + framesToCopy, 0, sizeof(float) * (framesToProcess - framesToCopy));
+
+ m_sourceFramesAvailable -= framesToCopy;
+ m_source += framesToCopy;
+ }
+
+private:
+ float* m_source;
+ size_t m_sourceFramesAvailable;
+};
+
+} // namespace
+
void SincResampler::process(float* source, float* destination, unsigned numberOfSourceFrames)
{
- ASSERT(m_blockSize > m_kernelSize);
- ASSERT(m_inputBuffer.size() >= m_blockSize + m_kernelSize);
- ASSERT(!(m_kernelSize % 2));
+ // Resample an in-memory buffer using an AudioSourceProvider.
+ BufferSourceProvider sourceProvider(source, numberOfSourceFrames);
+
+ unsigned numberOfDestinationFrames = static_cast<unsigned>(numberOfSourceFrames / m_scaleFactor);
+ unsigned remaining = numberOfDestinationFrames;
+ while (remaining) {
+ unsigned framesThisTime = min(remaining, m_blockSize);
+ process(&sourceProvider, destination, framesThisTime);
+
+ destination += framesThisTime;
+ remaining -= framesThisTime;
+ }
+}
+
+void SincResampler::process(AudioSourceProvider* sourceProvider, float* destination, size_t framesToProcess)
+{
+ bool isGood = sourceProvider && m_blockSize > m_kernelSize && m_inputBuffer.size() >= m_blockSize + m_kernelSize && !(m_kernelSize % 2);
+ ASSERT(isGood);
+ if (!isGood)
+ return;
+
+ m_sourceProvider = sourceProvider;
+
+ unsigned numberOfDestinationFrames = framesToProcess;
+
// Setup various region pointers in the buffer (see diagram above).
float* r0 = m_inputBuffer.data() + m_kernelSize / 2;
float* r1 = m_inputBuffer.data();
@@ -152,17 +212,14 @@
float* r4 = r0 + m_blockSize;
float* r5 = r0 + m_kernelSize / 2;
- m_source = source;
- m_sourceFramesAvailable = numberOfSourceFrames;
-
- unsigned numberOfDestinationFrames = static_cast<unsigned>(numberOfSourceFrames / m_scaleFactor);
-
// Step (1)
- // Prime the input buffer.
- consumeSource(r0, m_blockSize + m_kernelSize / 2);
+ // Prime the input buffer at the start of the input stream.
+ if (!m_isBufferPrimed) {
+ consumeSource(r0, m_blockSize + m_kernelSize / 2);
+ m_isBufferPrimed = true;
+ }
// Step (2)
- m_virtualSourceIndex = 0;
while (numberOfDestinationFrames) {
while (m_virtualSourceIndex < m_blockSize) {
@@ -315,12 +372,12 @@
*destination++ = result;
+ // Advance the virtual index.
+ m_virtualSourceIndex += m_scaleFactor;
+
--numberOfDestinationFrames;
if (!numberOfDestinationFrames)
return;
-
- // Advance the virtual index.
- m_virtualSourceIndex += m_scaleFactor;
}
// Wrap back around to the start.
Modified: trunk/Source/WebCore/platform/audio/SincResampler.h (98791 => 98792)
--- trunk/Source/WebCore/platform/audio/SincResampler.h 2011-10-29 01:31:04 UTC (rev 98791)
+++ trunk/Source/WebCore/platform/audio/SincResampler.h 2011-10-29 01:47:50 UTC (rev 98792)
@@ -30,6 +30,7 @@
#define SincResampler_h
#include "AudioArray.h"
+#include "AudioSourceProvider.h"
namespace WebCore {
@@ -44,10 +45,10 @@
// Processes numberOfSourceFrames from source to produce numberOfSourceFrames / scaleFactor frames in destination.
void process(float* source, float* destination, unsigned numberOfSourceFrames);
-
- // FIXME: we can add a process() method which takes an input source callback function for streaming applications
- // where the entire input buffer is not all available.
-
+
+ // Process with input source callback function for streaming applications.
+ void process(AudioSourceProvider*, float* destination, size_t framesToProcess);
+
protected:
void initializeKernel();
void consumeSource(float* buffer, unsigned numberOfSourceFrames);
@@ -72,6 +73,12 @@
float* m_source;
unsigned m_sourceFramesAvailable;
+
+ // m_sourceProvider is used to provide the audio input stream to the resampler.
+ AudioSourceProvider* m_sourceProvider;
+
+ // The buffer is primed once at the very beginning of processing.
+ bool m_isBufferPrimed;
};
} // namespace WebCore
